As more bands are to be supported in radio transceivers, which bands may span over a wide frequency range such as from 600 MHz to 3800 MHz, this can be met by a set of resonators. It is known that tuning an LC (inductor-capacitor) resonator more than one octave is difficult, which gives that a multitude of resonators may be demanded. This problem is further emphasized when carrier aggregation, i.e. the communication is performed on several different carriers simultaneously, which carriers may be spread anywhere in the wide frequency range.
LC resonators consume chip space, when implemented on-chip, and are fairly costly when implemented off-chip. It is therefore a desire to provide more flexible resonators.